A typical LCD has the advantages of portability, low power consumption, and low radiation. The LCD has been widely used in various portable information products such as notebooks, personal digital assistants (PDAs), video cameras, and the like. Furthermore, the LCD is considered by many to have the potential to completely replace CRT (cathode ray tube) monitors and televisions. An LCD generally includes a liquid crystal panel, a driving circuit for driving the liquid crystal panel, and a backlight module for illuminating the liquid crystal panel.
FIG. 8 is essentially an abbreviated circuit diagram of a typical driving circuit 10 of an LCD. The driving circuit 10 includes a number n (where n is a natural number) of gate lines 13 that are parallel to each other and that each extend along a first direction, a number m (where m is also a natural number) of data lines 14 that are parallel to each other and that each extend along a second direction orthogonal to the first direction, a plurality of thin film transistors (TFTs) 15 that function as switching elements, a plurality of pixel electrodes 16, a gate driving circuit 11, and a data driving circuit 12. The plurality of gate lines 13 and the plurality of data lines 14 cross each other, thereby defining an array of pixel units of the LCD. The gate driving circuit 11 is configured to provide scanning signals to the gate lines 13. The data driving circuit 12 is configured to provide data signals to the data lines 14.
Each TFT 15 is provided in the vicinity of a respective point of intersection of the gate lines 13 and the data lines 14. A gate electrode, a source electrode, and a drain electrode of the TFT 15 are connected to a corresponding gate line 13, a corresponding data line 14, and a corresponding pixel electrode 16 respectively.
Referring also to FIG. 9, this is a waveform diagram of driving signals of the driving circuit 10. G1-Gn show waveforms of scanning signals generated by the gate driving circuit 11. Vd shows a waveform of data signals generated by the data driving circuit 12. A driving method of the driving circuit 10 is as follows:
During a first frame, the gate driving circuit 11 generates a plurality of scanning signals 19, and applies the scanning signals 19 to the gate lines 13. The scanning signals 19 are high voltage signals. When one of the gate lines 13 has a scanning signal 19 applied thereto, the corresponding row of TFTs 15 are switched on by the high voltage. At the same time, the data driving circuit 12 applies a plurality of data signals Vd (which represent pixel data PD of the first frame) to the pixel electrodes 16 via the data lines 14 and the row of activated TFTs 15. Before a scanning signal 19′ of a second frame next to the first frame is applied to the gate line 13, the pixel data PD displayed on the row of pixel units remains the same. When the scanning signal 19′ of the second frame is applied to the gate line 13, the row of TFTs 15 are switched on again by the high voltage. At the same time, the data driving circuit 12 applies a plurality of data signals Vd′ (which represent pixel data PD′ of the second frame) to the pixel electrodes 16 via the data lines 14 and the row of activated TFTs 15. Thereby, the row of pixel units display the pixel data PD′ of the second frame.
However, because a response speed of liquid crystal molecules at the pixel electrodes 16 of the LCD is low, a residual image phenomenon may occur. In particular, when the data signals are changed from Vd to Vd′, the liquid crystal molecules may be unable to track the variation within a single frame period, and instead produce a cumulative response during several frame periods.
What is needed, therefore, is a driving circuit and a driving method of an LCD that can overcome the above-described deficiencies. What is also needed is an LCD using such a driving circuit.